LP powered AC unit

[daveb]

Originally Posted by chromisdesigns

Heat gain and insulation in the van vs house is probably the biggest factor. When I was living on my sailboat, like many others I had adapted a small window A/C unit to fit in one of the hatches. It was barely adequate. The same unit could cool a large room in a house without any difficulty.

I really wouldn't expect the holy grail, yet know those who have done this and they claim it works quite well. Probably several factors that come into play. I actually don't think a small window type A/C would work that well with the PH up in 90* temps anyway. What I'd like is just cool air blowing towards me when sleeping. The idea of a generator running all night sucks but what other choice do you have except shorpower or find cool weather

[TomH]

Originally Posted by daveb

...what other choice do you have except shorpower or find cool weather ...

This one:

http://www.chilitechnology.com/

It cools, but doesn't remove humidity, so it can make your body feel a bit damp/clammy. Also, it cools only the side of you that's down. You can't wrap it around you to cool the top side of yourself as it depends on direct contact with pressure.

[E350]

Originally Posted by stanw909

I was thinking that having a chiller like an lp fridge with dc fans to desperse the coolness coupled with low gas and electric consumtion could work but the van would have to be level like any gas fridge and probably use much more gas than a closed fridge /freezer. Thanks for the article maybe I 'll tackle the problem some day.

I think I proposed this in another thread and was shot down. But I don't see why it wouldn't work. Moving air over a body sleeping is almost enough. Cool moving air should be sufficient. So, I encourage you to do the experiment and please report back to all of us.

[Ford_6L_E350]

I think you are overestimating the amount of cooling that is done be an LP refrig. Yes it can cool a refirg quite well, but that is a small, well insulated space. And the flame runs continuously. And the refrig works best to maintain a cool environment, not to cool it down from 90.

Try an experiment, open an LP refrig and turn it on. Come back an hour later and see how much cool air there is. Try it again at 90 degrees.

Mike

[E350]

Originally Posted by Ford_6L_E350

I think you are overestimating the amount of cooling that is done be an LP refrig. Yes it can cool a refirg quite well, but that is a small, well insulated space. And the flame runs continuously. And the refrig works best to maintain a cool environment, not to cool it down from 90.

Try an experiment, open an LP refrig and turn it on. Come back an hour later and see how much cool air there is. Try it again at 90 degrees.

Mike

I don't have an LP frig but I would like to hear the results of the experiment. With one addition, run a 12v computer or other low voltage fan over the part that is the coolest in the frig and let us know.

I thought that the frig would have to have a drip line outside, because I am guessing that condensation will form. But I really don't know anything.

I do know a story about Edison. He asked some new hires to measure the volume of a light bulb. They were still madly calculating the volume of that irregular shape when he returned in an hour, whereupon he filled the bulb with water which he then poured into a graduated cylinder, obtaining the volume.

So I say, do the experiment.

[Chance]

Originally Posted by daveb

I still can't figure why a home window A/C can be so efficient and why someone can't design a small compact unit even if it were 2 piece for our vans based on a similar design. Why my Starcool pulls so much and cools so little compared to a home window unit is beyond me.

How much does it pull?

Sportsmobile-provided air conditioners are much bigger in capacity. Small window units like mine can be as small as 5000 BTU/hour. That's a fraction of capacity. They can be very efficient but mostly it's the smaller size.

[Chance]

Originally Posted by E350

I don't have an LP frig but I would like to hear the results of the experiment. With one addition, run a 12v computer or other low voltage fan over the part that is the coolest in the frig and let us know.

I thought that the frig would have to have a drip line outside, because I am guessing that condensation will form. But I really don't know anything.

I do know a story about Edison. He asked some new hires to measure the volume of a light bulb. They were still madly calculating the volume of that irregular shape when he returned in an hour, whereupon he filled the bulb with water which he then poured into a graduated cylinder, obtaining the volume.

So I say, do the experiment.

I wouldn't bother. An electric RV fridge uses about 1/10th the power or less of a small window AC. That says plenty/enough about cooling capacity. It wouldn't even start to cool a van.

[daveb]

Originally Posted by Chance

How much does it pull?

Sportsmobile-provided air conditioners are much bigger in capacity. Small window units like mine can be as small as 5000 BTU/hour. That's a fraction of capacity. They can be very efficient but mostly it's the smaller size.

A bunch. I agree that window types are rated for what they are but it just seems that the Starcool for what it's rated for is lame. Maybe mine is FU? Works great on the road, not on shore power. It does work OK is on all day in the shade.

[Chance]

Originally Posted by stanw909

I was thinking that having a chiller like an lp fridge with dc fans to desperse the coolness coupled with low gas and electric consumtion could work but the van would have to be level like any gas fridge and probably use much more gas than a closed fridge /freezer. Thanks for the article maybe I 'll tackle the problem some day.

This could be done for certain, but in the past it hasn't proven to be practical. It has been tried on experimental basis for automobile AC where the heat source was "free" from engine heat, and even then it wasn't practical. The biggest problem, aside from very expensive, is that the equipment was so large and heavy for the needed capacity that it made the car less fuel efficient than if the engine powered a standard compressor system.

For houses where size and weight is not as critical it has been used for solar air conditioning with limited success. Many decades ago the University of Florida had a solar house where the Air Conditioner ran off hot water provided from solar panels (thermal type, not electric). As I recall the equipment was huge compared to typical residential AC. And the cost would have been prohibitive. If a propane system was going to be practical, we'd probably first see residential ACs running off natural gas because size and weight wouldn't be as much of an issue. Also we wouldn't have to worry about the AC staying level although that can be overcome to some degree.

As a point of reference, think about how much cheaper and simpler an electric RV refrigerator is compared to a propane absorption unit. Compressor fridge can be so efficient that it's becoming easier to run them off batteries versus installing a propane system if that's all you were going to use propane for. Even with propane in RV I think I'd go with all electric refrigerator anyway.


In my opinion the long-term answer to the problem you are bringing up may be in affordable fuel cell technology. I remember reading that a company had been awarded a contract to study a fuel cell electricity generator for RVs (think it was Onan but not sure). Cost is still prohibitive. The other possibility may be more efficient and lower cost batteries. Lithium is getting close. As I posted in a different thread, Roadtrek is already marketing a battery system that may be able to run a small window-unit-size AC overnight.

[daveb]

I'm also waiting for battery and solar tech to advance. I can't wait for a reasonably priced high AH lithium that takes up a small space to be designed. My Starcool works well enough that provided it can operate all day W/O shore power, I'm good. For now I just don't see much out there except driving to the cool mountains and enjoying the cooler months.

Oh BTW I did look at those cooling mats Tom.